JPH0322182A - Automatic contour tracking method in cad - Google Patents

Abstract

PURPOSE:To make operation easy by calculating an angle between a final selecting element and a next selection candidate element, preferentially selecting one element with the smaller angle out of the plural selection candidate elements when contour tracking is executed along an inner track and selecting one element with the larger angle when the contour tracking is executed along an outer track. CONSTITUTION:The contour tracking is executed like an arrow from a start element BA and arrives at a first end point (a). At such a time, the angle between a final selecting element Ca in this side of the end point (a) and next selection candidate elements aD and aE in a counter-clockwise direction is calculated with the final selecting element Ca as a reference. Based on this angle and either an inner or outer tracking direction, the selection of the next selection candidate element is determined according to a prescribed condition. Namely, when the contour tracking is executed along the inner track, one element with the smaller angle is selected and when the contour tracking is executed along the outer track, one element with the larger angle is selected preferentially out of the plural selection candidate elements. Thus, the operation is made easy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an automatic contour tracking method in CAD. [Prior Art] Contour tracking of figures on a display has conventionally been performed semi-automatically. When tracing the outline of the figure on the display in FIG. 19, it is possible to trace the element line segment from the start point S to the end point a, but the tracking movement stops at the end point a. At this time, when the operator instructs the outside ■, the graphic element is automatically traced to the next end point b, and at this position the operator again instructs which direction to move. [Problems to be solved by the invention] As mentioned above, in the case of a semi-automatic tracking function, each time tracking stops at an end point, an operator must be instructed as to which direction to pursue, resulting in poor operability. There was a defect,
The present invention aims to eliminate the above defects. [Means for Solving the Problems] In order to achieve the above object, the present invention specifies a start element from among consecutive elements of a figure on a display, and also sets the tracking direction and whether it is an inside or outside rotation. In the method of automatically obtaining contour data by sequentially determining and selecting successive elements based on the start element according to the tracking direction and whether they are inward or outward, when the next selection candidate element appears on the final selected element. , find the angle θ between the final selected element and the next selection candidate element, and when the contour tracking is inward, give priority to the one with the smaller angle θ, and when the contour tracking is outward, give priority to the one with the larger angle θ. One of the selection candidate elements is selected. [Example] The structure of the present invention will be described in detail below with reference to the attached explanatory drawings.

First, an outline of the present invention will be explained with reference to FIGS. 1 and 2.

Enter label 1 in Figure 1 into the automatic contour tracking program,
While looking at the figure displayed on the display, the operator selects a start figure element to start automatic contour tracking, and a trace. Select and decide the direction and whether to track the outer contour or inner contour, and based on these decisions, hit a point on the display with the cursor. Depending on the hit position of this cursor, each of the above selected elements is automatically set in block 2. Next, the process moves to block 3, where a contour processing program is executed, and end point processing and angle setting, which will be described later, are performed. When the cursor hits the position marked ■ on the display, the outer contour of the figure is traced in the arrow direction with line segments A and B as starting elements, and the figure elements resulting from the tracing are shown in Figure 2B. become that way. When you hit the cursor on the ■ position on the display, the inner contour is drawn in the direction of the arrow, and the traced graphic element becomes as shown in Figure 2C. In block 3 in Figure 1, the contour automatic tracking function sequentially identifies and selects consecutive elements from the graphical elements on the displayed figure, and copies them as contour data to the specified layer (hierarchy in information file management). ．． The contour shapes copied at this time are rearranged so that geometric elements such as straight lines and arcs are continuous. Next, the start element designation program of block 2 in FIG. 1 will be explained in detail.

In automatic contour tracing, it is first necessary to specify with a cursor which element (straight line/arc) the tracing will start from, as well as the contour tracing direction and tracing mode (inward/outward).

The pointing point specifying the start element also means the tracing direction and the inner/outer direction of the contour.

Here, if the flag representing inner/outer rotation is CCW, when the indicated element, that is, the graphical element closest to the cursor hit position is a straight line, its end points are A, B, etc., as shown in FIG. When the cursor indication point is P, the angle between the end point near P and the end point far from P (the angle BAP in Figure 6) is smaller than π is considered an inward rotation. , set 1 to CCW. Then, when it is larger than π, it is regarded as an outer circumference, and -1 is set in CCW. When the specified element is a circular arc as shown in Figure 7, the point between P and a point of arbitrary length of a tangent line drawn from that end point to the actual point of the arc, centering on the end point closest to P. The angle O (angle A' BP in Fig. 7 A. Angle B' AP in Fig. 7 B) is π
When it is smaller than π, it is set as an inner loop, and CCW is set to 1. When it is larger than π, it is set as an outer loop, and CCW is set to -1. The tracking direction is determined so that the end point closer to the designated point P is the end point of the start element. In the case of Figure 6, point A is determined to be the terminal point, the tracking direction is determined to be the arrow direction, and Figure 7
In this case, the -A point is determined to be the terminal point, and the tracking direction is determined to be the arrow direction. Next, the end point processing of the contour tracking processing program in block 3 in FIG. 1 will be explained in detail. In FIG. 3, starting from the starting element BA, it is traced as shown by the arrow until it reaches the first end point a. At this time, the process of determining the next graphical element to be tracked is end point processing,
This process calculates the angle θ between the final selected element Ca before the end point a and the next selected candidate elements aD and aE in a counterclockwise direction with respect to the final selected element Ca as a reference, and this angle θ and the tracking direction are The selection of the next selection candidate element is determined according to predetermined conditions based on whether it is the outer circumference or the outer circumference. The process of obtaining the above-mentioned θ is called angle setting. An outline of the end point processing will be explained with reference to the diagram shown in FIG. Find each counterclockwise angle based on . The angle on the element ab side is θaD
(see Figure 4A), and the angle on the element aE side is θaE (see Figure 4B), in the case of outer tracking, the selected angle θa = MAX (θaD, θaE) = θa
Take the condition that D. Therefore, in this case, element aD is tracked. In Figure 3, it then passes point F and reaches end point b. At this time, the final selection element FG and the next selection element bH
Find the counterclockwise angle θb with respect to FG. In the case of outer tracking, select one that satisfies the condition θb>π. Therefore, in this case, element bH is tracked. Thereafter, it will be tracked in the same way and will pass through the end points c and d. The tracking results are BnA→C→a→D→F→b→H-
4c → d4B, resulting in a contour figure as shown in Figure 2B. When the pointing point P is set as shown in Fig. 5, the start element is set to BA in block 2 of Fig. 1, the tracking direction is set to the B-4A direction, and it is set to the inner direction. , starts from the start element BA, is traced as shown by the arrow in the figure, and reaches the first end point a. In this case, since it is an inner rotation, the angle to be selected is θa = Min(θaD, θaE) = θaE. Therefore, here we will track element aE. Next, reach the end point e. In this case, since it is an inner rotation, θ
Take the one that satisfies the condition e x π. Therefore, we will now track element ef. Subsequently, it will be traced in the same way and will pass through the end points f and d. The tracking result is B-+A-+C-
+a-+E-4e→f-+d→B, resulting in a contour figure as shown in FIG. 1C.

Next, end point processing, that is, how to determine tracking elements will be explained in detail.

FIG. 8 shows the preconditions for the next selection candidate element. The element that supplies the terminal point of the final selection element in Figure 8A, or the terminal point of the final selection element on the element in Figure 8B, or on the final selection element in Figure 8C. An element that has either endpoint is the condition for the next selection candidate element. When the angle between the final selection element and the next selection candidate element is θ, with each point in FIG. 8 as the center, if the flag CCW is 1 (inward rotation), -4
B-+C), and when CCW is -1 (outer rotation), preferentially select the one with larger θ (A→B- in Figure 9B) E). As shown in FIGS. 10A and 10B, when one or both elements are circular arcs (including circles), the angle formed by the tangent and the straight line or both tangents at both end points is θ.

As shown in Figure 1l, if there are multiple next selection candidate elements on the final selection element, priority is given to the one closer to the starting point of the final selection element than the value of θ. However, CCW is 1 (inner rotation)
When θ is π, when CCW is -1 (outer rotation), θ〉
Assume that π is satisfied. How to determine the priority order when θ is the same as that of multiple next selection candidate elements at the same point will be explained with reference to FIG. The criteria for determining when θ is the same at the same point is, when the next selection candidate element is a circular arc, its radius and the direction of the start point/end point (nf (1 for counterclockwise rotation, -1 for clockwise rotation) and CCW (inner or outer rotation) values are used. When the next selection candidate element is a straight line, the radius is considered to be an infinite circular arc for convenience. -Insert CCW. And C.C.
When W and nf match, the one with the larger radius, CCW and n
If f does not match, give priority to the one with the smaller radius, and C
Priority is given to cases where CW and nf do not match.

From the above conditions, when CCW=1 (inner rotation), among the elements of nf=1 (when CCW and nf match),
Select arc d with large radius. nf=-1 (CC
When W and nf do not match), arc a (small radius) is selected. In this case, the priority is e → d-4c
-4b→a (highest priority) When CCW=-1 (outer rotation), select arc b (large radius) among the elements with nf=-1 (when CCV and nf match).

Select arc e (small radius) in the element where n f = 1 (when CCV and nf do not match). In this case, the priority order is a→b→C→d→e (highest priority order). Next, we will explain which value to take when the angle θ is found to be zero or 2π. When the final selected element is a circular arc, the radius (br) and the direction of the start and end points (bf) are used as criteria for judgment. If it is a straight line, set bf=o and process it separately. When the selected candidate element is a straight line: (1) When the final selected element is a straight line (bf=o), it is judged as the same element and removed from the candidates (see Figure 13) (2) When the final selected element is an arc If bf=1 (counterclockwise), it is zero (see Figure 14),
If bf=-1 (clockwise) then 2? c (see Figure 14)
It is processed as follows. When the selected candidate element is a circular arc, its radius is nr, and the start and end point direction when the end point is the starting point is nf.(1) When the final selected element is a straight line, CCW=1 when CCW#nf (inner rotation) then 2π (see Figure 15B),
If ccw=-1 (outer rotation), it is treated as zero (see FIG. 15A).

When CCW=nf, if CCW=1 (inside), zero (see Figure 6 A), C
If CW=-1 (outer rotation), it is processed as 2π (see FIG. 16B).

(2) When bf#nf and br=nr (concentric circles),
They are judged to be the same element and removed from the candidates (see Figure 17). (3) When bf #nf b r > n r (first
(See Figure 8) If bf=1, it is treated as 2π, and if bf=-1, it is treated as zero.

(4) When bf=nf or br<nr (see Figure 18), if bf=1, it is treated as zero, and if bf=-1, it is treated as 2π. [Effects] Since the present invention is configured as described above, it has the advantage that the inner and outer directions can be automatically determined and the outline of a graphic element can be automatically tracked.

[Brief explanation of drawings]

FIG. 1 is a flowchart, FIGS. 2 to 18 are explanatory diagrams, and FIG. 19 is an explanatory diagram of the prior art.

Claims (9)

[Claims] (1) Indicate the start element from among the continuous elements of the figure on the display, set the tracking direction and whether it is an inner or outer rotation, and select whether the continuous elements starting from the start element are traced in the inner or outer rotation. In the method of automatically obtaining contour data by discriminating and selecting in order according to seek,
A feature is that when the contour tracking is inward, priority is given to the one with the smaller angle θ, and when the contour tracing is in the outer direction, priority is given to the one with the larger angle θ, and one of the multiple selection candidate elements is selected. Automatic contour tracking method in CAD. (2) The automatic contour tracking method in CAD as set forth in item 1, characterized in that the element of the figure closest to the hit position of the cursor on the display is designated as the start element. (3) When the specified start element is a straight line, its end points are A and B, and the cursor hit position is P, the end point closer to P is the center, and the end point farther from P and P. Items 1 and 2, characterized in that when the angle is smaller than π, it is an inner turn, and when it is larger than π, it is an outer turn.
Automatic contour tracking method in CAD described in Section 1. (4) If the specified start element is an arc, the angle formed by the point on the tangent line drawn from the end point nearer to the cursor hit position P toward the actual arc and the above P. 2. The automatic contour tracking method in CAD according to the above items 1 and 2, characterized in that when is smaller than π, the inner turn is taken, and when it is larger than π, the outer turn is taken. (5) The automatic contour tracking method in CAD according to items 1 and 2, characterized in that the tracking direction is set by setting the end point closer to the cursor hit position P as the end point of the start element. (6) When one or both of the final selection element and the next selection candidate element is a circle or an arc, the angle between the tangent at both end points and the straight line or both tangents is set to θ. 1. Automatic contour tracking method in CAD according to item 1. (7) When there are multiple next selection candidate elements on the final selection element, if the condition that the angle θ is smaller than π for the inner rotation and larger than π for the outer rotation is satisfied, the angle θ CAD according to item 1, characterized in that the final selection candidate element is selected with priority over the value of
An automatic contour tracking method in (8) At the same point, when the angle θ is the same and the next selected element is a circular arc, specify the radius, the direction of the starting point and end point when the same point is the starting point, and whether it is inward or outward. 2. The automatic contour tracking method in CAD according to item 1, characterized in that the priority is determined as a criterion. (9) When the outer direction is counterclockwise and the inner direction is clockwise, if the directions of these tracking modes and the directions of the starting and ending points of the arc match, the one with the larger radius of the arc,
When the direction of the tracking mode and the direction of the start and end points of the arc do not match, priority is given to the arc with the smaller radius, and the case where the direction of the tracking mode and the direction of the start and end points of the arc do not match is given priority. 9. The automatic contour tracing method in CAD according to item 8.